You guys that install Hemi/LS engines in your JKs make me envy you. I am more than content with what I have now but if I had money that was cluttering up my garage I would do a V8 swap for sure; not the juice kind either.

Cant comment about an LS or Hemi as I havent driven a jeep powered with one. I imagine it would be awesome.....but just too much $ to justify for me. I have the RIPP gen II SC, run 37" (heavy) Toyo OC MT, 5:13 gears, and it is my daily driver. Anyone who thinks you have to be at 5000 rpm to get to positve boost is misinformed. I run a boost/vacuum gauge because the more I stay on vacuum side, the better gas milage I get. However, from any gear, if I step on gas pedal, I get as much as 6psi boost. In 6th gear, at 70 MPH, I am running at 2800 rpm. If I step on skinny pedal, my boost gauge imediately jumps to 1-3psi boost and I never get close to 5000 rpm. Do I have the power of a V-8, probably not, but I am very happy with the RIPP setup.

The 6.4 hemi is a monster, I can only imagine what that would be like. I have the 5.7 in my commander and do really like it. It is a blast to drive and the fastest vehicle I have ever owned (mainly had jeeps and trucks).

I get 14-16mpg in the commander on the highway typically, 11-12 around town. I get 15-16 with 4.10's and 35's on the jk, 14-15 around town. When I had 33's I could easily get 16-18 on the highway. I am getting 5.13's within a month and expect to see my mileage improve. I might decide I don't need more power. I have never encountered a situation offroad where I needed more power than the stock 3.8 makes. I have wanted lower gearing though and the 5.13's should help but my next step will be a rubicrawler. My biggest concern with the hemi is the heat. My commander will hit a coolant temp of 230+ on the highway, seems hot to me but chrysler says it is normal. The transmission with cooler pulling my 2700# trailer will hit 180-190, again seems hot to me but chrysler says its normal. I would think these temps will lead to decreased life.

You can do a motech swap fairly cheap if you don't want a lot of the modern conveniences such as cruise control. But if you want it to look, act, and drive just like it came from the factory you are not gonna do it for $5k. But if you want cruise, a better radiator (for anything over 5.3l), and to reuse your stock transfer case you are at close to $7K just for the kit plus you have to find an engine and transmission (which you can find great deals on)I would still think 3k for a newer lower mileage engine and transmission would be about where you would be, you might even be able to find better deals on the engine/transmission. So, you are still at about $10k for an LS swap doing your own work. If you have motech or another shop do the work you will easily see 15-20K.

The 6.4 hemi is a monster, I can only imagine what that would be like. My biggest concern with the hemi is the heat.

The 6.4 is beautiful, something that needs to be experienced to be adequately appreciated. My 6.4 with 4.10 gears and 35" tires has gotten between 14.1 mpg and 16.8 mpg, and I have had no problems with heat. I got mine from AEV, and I think that both AEV and Burnsville have these figured out now. I would not get one from a shop that does them as a sideline.

Last weekend I took an editor friend on a wheeling trip to the top of a 10,000 foot tall mountain, up a long steep dirt road. The last time I took this trip was a few years ago, in a two door 2010 JK with 35" tires and 5.38 gears. I did about half the trip in high range 4-wheel drive, and at that point a warning light came on on the dash that said "HOT OIL". It is a light that comes on when automatic transmission oil temperatures get too high. I had to stop and let it cool, then shift into low range 4-wheel drive to complete the trip. This time I did the whole trip in high range 4-wheel drive, and I never saw any warning lights for trans temp, or other heat problems. The big Hemi practically idled its way up the mountain, and never got hot. In that situation the Hemi was better than a stock engine JK as far as heat goes.

Theoretically, the cheapest way to get a Hemi in a jeep is if it was a factory option. The 5.0 Coyote in an F 150 is only $1000 more than the 3.7 , V6.

If we'd petition Jeep long enough to convince them there is a market, they'll do it.

I'd love a Hemi with that six speed manual!

I just got an F150 with the 5.0L. Its weight is exactly the same as my '09 JKUR, 5500 lbs. The difference in performance on the highway is significant, and the 5.0L gets significantly better mileage. So, I can imagine a proper V8 in the JK would be a very satisfying drive. In most cases I've seen the V8/trans combos that can be installed don't weigh significantly more (sometimes less) than the 3.8L & auto trans in the earlier JKs. I haven't seen an LS conversion yet, but the few Hemi conversions I've looked at are really slick. A local guy here had one done a number of years ago and had constant overheating issues. However, I don't hear that much about it being a common issue.

If it's something you could do yourself and you were able to nab an engine fairly cheap, it'd probably be worth it. I've driven in a 5.7L Hemi JK and while it definitely has more umph, it's not worth $20k.

I see alot of people wanting diesel engines in their Jeep. I'm not sure it would be all that great of a conversion though. I've owned several diesel pickup trucks, and now own a 2012 Ram with a 6.7 Cummins that makes 800 ft lbs of torque. So, being as I have both a Cummins, and a 6.4 Hemi in the garage, which one would I choose for the ultimate Jeep engine? The Hemi, hands down. The diesel makes lots of torque when its out on the highway, pulling a load, with the turbo spooled up. But the diesel is a dog right off the line, and around town, due to turbo lag. Compared to a 6.4 almost anything is a dog though.

I see alot of people wanting diesel engines in their Jeep. I'm not sure it would be all that great of a conversion though. I've owned several diesel pickup trucks, and now own a 2012 Ram with a 6.7 Cummins that makes 800 ft lbs of torque. So, being as I have both a Cummins, and a 6.4 Hemi in the garage, which one would I choose for the ultimate Jeep engine? The Hemi, hands down. The diesel makes lots of torque when its out on the highway, pulling a load, with the turbo spooled up. But the diesel is a dog right off the line, and around town, due to turbo lag. Compared to a 6.4 almost anything is a dog though.

All good points.

I guess what I am getting at is my previous Jeep was a 95 YJ with the 4.0L. I know it had less horsepower and less torque than the 3.8L in my 07 JK. The JK's power band is more in the mid to upper rpm's whereas the 4.0L's is more in the low to mid rpm's.

While I certainly appreciate the extensive testing, excellent customer support, etc. that RIPP provides, everything that I have been able to gather indicates an improvement to the 3.8L at the mid to upper rpm's. In other words, it makes the 3.8L even more ricey. I am wanting to get back to a more tractor type of engine, with that type of feel instead.

While and LS is certainly not a rice engine, it is a sports car engine. It just seems like a strange thing to think about a corvette slowly crawling over obstacles, especially at elevated rpm's. Granted, it wouldn't be crazy rpm's, but still, not quite the easy going idling.

There is no doubt a hemi or ls would be faster, and be make the Jeep more like a sports car, that's not really what I feel is lacking.

I have to agree with you there Jim. Most places are charging $20,000 to $25,000 for a hemi swap or even an LS swap. That kind of money buys another Jeep. If the cost was $5,000 to $$7,000, it would be a different story. I personally cannot justify replacing the 3.8L in favor of a hemi for that kind of money, especially when there isn't a gaping hole in the side of the block or some other catastrophe.

Magnuson / AEV superchargers are an interesting, more affordable option.

depends on how you plan it. i bought a 2007 unlimited with approx 77000 miles on it with the intention of doing the swap. it was pristine highway vehicle, never seen offroad and must people think it is a new jeep and i got it for 16K, added the hemi myself for around 15K and now have a awesome jeep with a hemi for around 31K, less than alot of people pay for a new one. i will add dana 60s and still be around 40-45K which i have seen new jeeps sell for. everybody has different wants and needs and whats worth it to one is not to the next.. i'm very happy with my finished product when my wife doesnt beat me to driving it....